title: Validity of medical record documented varicella-zoster virus among unvaccinated cohorts.
abstract: BACKGROUND
  A varicella diagnosis or verification of disease history by any healthcare provider is currently accepted for determining evidence of immunity by the Advisory Committee on Immunization Practices (ACIP).
  
  
  OBJECTIVE
  To examine the accuracy of medical record (MR) documented varicella history as a measure of varicella-zoster virus (VZV) immunity among unvaccinated individuals born after 1980. We also assessed methods to practically implement ACIP guidelines to verify varicella history using medical records.
  
  
  METHODS
  As part of a larger cross-sectional study conducted at three Philadelphia clinics from 2004-2006, we recruited 536 unvaccinated patients aged 5-19 y (birth years: 1985-2001). Varicella history was obtained from three sources: parent/patient interview, any MR documentation (sick and well visits) and MR documentation of a sick visit for varicella. All participants were tested for VZV IgG. For each source and three age groups (5-9, 10-14, 15-19 y old), positive predictive value (PPV) was calculated. Specificity of varicella history was compared between different sources using McNemar's Chi-square.
  
  
  RESULTS
  Among participants aged 5-9, 10-14 and 15-19 y the PPV for any MR documentation and sick visit diagnosis were 96% and 100%, 92% and 97%, and 99% and 100%, respectively. The specificity for sick visit documentation was higher than any MR documentation and patient/parent recall among all age groups; however, these differences were only statistically significant when comparing sick visit documentation to parent/patient recall for 10-14 y olds.
  
  
  CONCLUSIONS
  Sick visit documentation of varicella in the MR is an accurate predictor of varicella seropositivity and useful for confirming disease history among unvaccinated persons (birth years: 1985-2001). This method is a practical way to verify varicella history using the ACIP guidelines.
authors.affiliation: Varicella Active Surveillance Project, Division of Disease Control; Philadelphia Department of Public Health; Philadelphia, PA USA.
authors.forename: Salini
authors.initials: S
authors.lastname: Mohanty
authors.forename: Dana
authors.initials: D
authors.lastname: Perella
authors.forename: Aisha
authors.initials: A
authors.lastname: Jumaan
authors.forename: Donovan
authors.initials: D
authors.lastname: Robinson
authors.forename: Christine M
authors.initials: CM
authors.lastname: Forke
authors.forename: D Scott
authors.initials: DS
authors.lastname: Schmid
authors.forename: Mia
authors.initials: M
authors.lastname: Renwick
authors.forename: Foram
authors.initials: F
authors.lastname: Mankodi
authors.forename: Barbara
authors.initials: B
authors.lastname: Watson
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Fiks
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood*; D002644:Chickenpox / Q000276:immunology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D014645:Herpesvirus 3, Human / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008487:Medical History Taking; D008499:Medical Records; D015143:Philadelphia; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G
keywords: chickenpox; immunity; medical record documentation; unvaccinated; varicella